Companion water heater

ABSTRACT

A hot water heater appliance includes a boiler, a companion water heater and a controller. The controller is configured to control the water heater appliance in response to a scheduled plurality of performance modes based on a preset schedule. A first performance mode is scheduled to be performed at an expected low usage time and a second performance mode is scheduled to be performed at an expected high usage time relative to the expected low usage time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/757,056, filed on Jan. 25, 2013, titled “COMPANION WATER HEATERFOR WM97+ GAS-FIRED BOILERS,” the disclosure of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to a hot water heater. Moreparticularly, the present invention relates, for example, to a waterheater for use with a suitable boiler.

BACKGROUND OF THE INVENTION

Generally, domestic hot water is supplied via a water heater appliancethat is sized for the expected hot water draw. Insufficient hot watercan strongly negatively affect the comfort of any occupants of theresidence and lead to frustration and/or an expensive replacement of theappliance. However, excessive hot water capacity can lead to energyinefficiencies and poor performance. Examples of water heater appliancesinclude traditional hot water heater tanks, ‘instant’ hot water heaterswhich are often called ‘tankless water heaters’, and indirect waterheaters. Commonly, each of these water heater appliances are acompromise between water heater performance values such as: ‘peak draw’performance; ‘continuous draw’ performance; ‘first draw’ performance;efficiency; operating cost; and initial cost.

Peak draw performance is a measure of how much hot water is availableduring peak demands. This is normally an increased amount over what theappliance can produce continuously (e.g., continuous draw performance)based on the amount of hot water the appliance is storing. When thispeak demand is at the beginning of the hot water draw it is considered a“First Draw Performance”. A Peak Draw Value can be expressed as gallonsper minute (GPM) at a specific temperature rise for a limited period oftime. This temperature rise is a measure of the difference intemperature between the incoming water supplying the water heaterappliance and the hot water supplied by the water heater appliance.After that time the temperature of the water delivered will drop.

While conventional water heater appliances attempt to create a goodbalance of water heater performance values, they typically fail toefficiently provide both good peak draw and continuous draw (or steadystate) performance. Accordingly, there is a need in the art to improvethe water heater appliance.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the presentinvention, wherein aspects of a water heater appliance are provided.

An embodiment of the present invention pertains to a hot water heaterappliance. The hot water heater appliance includes a boiler, a companionwater heater and a controller. The controller is configured to controlthe water heater appliance in response to a scheduled plurality ofperformance modes based on a preset schedule. A first performance modeis scheduled to be performed at an expected low usage time and a secondperformance mode is scheduled to be performed at an expected high usagetime relative to the expected low usage time.

Another embodiment of the present invention relates to a companion waterheater. The companion water heater includes a hot water storage tank, aheat exchange coil, a lower sensor, an upper sensor, a circulator pump,and an insulating jacket. The heat exchange coil is disposed in the hotwater storage tank. The lower sensor is disposed in thermal contact witha lower portion of the hot water storage tank. The upper sensor isdisposed in thermal contact with an upper portion of the hot waterstorage tank. The circulator pump is to urge a flow of a heating fluidto circulate between a boiler and the heat exchange coil. The insulatingjacket is disposed around, below, and above the hot water storage tank.The insulating jacket has an expanded polypropylene insulation layer andthe insulating jacket includes a plurality of segments releasablyfastened to each other.

Yet another embodiment of the present invention pertains to a method ofheating water in a water heater appliance. In this method, a pluralityof upper portion temperature measurements are received over a timeperiod at a controller configured to control the water heater appliance.The plurality of upper portion temperature measurements are associatedwith an upper portion of a hot water storage tank disposed in the waterheater appliance. A plurality of lower portion temperature measurementsare received over the time period at the controller from a lower portionof a hot water storage tank. An upper temperature profile over the timeperiod is determined by the controller based on the plurality of upperportion temperature measurements. A lower temperature profile over thetime period is determined by the controller based on the plurality oflower portion temperature measurements. A domestic hot water usageamount is determined by the controller in response to at least one ofthe upper temperature profile and the lower temperature profile being ata relatively steeper slope than a standby temperature profile. The wateris heated in response to the domestic hot water usage being relativelygreater than an amount of thermal energy in the hot water storage tank.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross sectional and exploded view of a hot waterheater appliance suitable for use with an embodiment of the presentinvention.

FIG. 2 is a block diagram of a system architecture for the hot waterheater appliance depicted in FIG. 1.

FIG. 3 is a block diagram of a controller for the hot water heaterappliance depicted in FIG. 1.

FIG. 4 is a block diagram of a method of controlling the hot waterheater appliance according to an embodiment of the present invention.

DETAILED DESCRIPTION

Various embodiments of the present invention provide for an improved hotwater heater appliance that is configured to efficiently provideexcellent peak draw and steady state performance and a method ofcontrolling the hot water heater appliance. In some embodiments, the hotwater heater appliance includes a variety of performance modes tooptimize one type of performance over others. The hot water heaterappliance may be configured to remain in a particular performance modeor change from one mode to another depending on a variety of factorssuch as, for example, a pre-programmed timed schedule, learned schedule,domestic hot water (DHW) draw, and the like. It should be understood,however, that the present invention is not limited to any oneperformance mode and is generally more efficient and better able to meetDHW draws than conventional water heating appliances. Preferredembodiments of the invention will now be further described withreference to the drawing figures, in which like reference numerals referto like parts throughout.

Turning now to the drawings, FIG. 1 is a partial cross sectional andexploded view of a hot water heater appliance 10 suitable for use withan embodiment of the present invention. As shown in FIG. 1, the hotwater heater appliance 10 includes a boiler 12, a companion water heater14, and a user interface/controller 16/18. In general, the boiler 12 isconfigured to provide the energy to heat the DHW. The companion waterheater 14 is configured to receive the energy from the boiler 12 to heatthe DHW. The user interface 16 is configured to provide for two waycommunication between a user and the controller 18. In this regard, theuser interface 16 includes a display and keys or other such output andinput devices. In a particular example, the display includes variousmenus to select and control modes of operation for the boiler 12 and/orthe hot water heater appliance 10. It is a particular advantage of someembodiments that the user interface/controller 16/18 automaticallysenses installation of the companion water heater 14 and thenautomatically provide an additional menu for the companion water heater14. The controller 18 is configured to control the hot water heaterappliance 10.

The boiler 12 includes any suitable boiler or device capable ofgenerating delivering energy to the hot water heater appliance 10. Moreparticularly, the boiler 12 is configured to provide heated watersuitable to be transported to the location of energy need. Examples ofsuitable boilers include: gas fired; oil fired; electric; solar;geothermal; or the like. In a particular example, the boiler is a gasfired boiler configured to heat a supply of water that is thencirculated between the boiler 12 and the companion water heater 14. Aspecific example of a suitable boiler includes the WM97+ manufactured byWeil-McLain of Michigan City, Ind. 46360-2388 USA.

As shown in the exploded portion of FIG. 1, the companion water heater14 includes an insulated jacket 20, hot water storage tank 32, sensors34 and 36, mixing valve assembly 38, circulator pump 40, boilerconnectors 42, temperature and pressure relief valve (T&P relief valve)44, domestic cold water (DCW) in connector 46, and domestic hot water(DHW) out connector 48. The insulated jacket 20 includes any suitableinsulating material. In addition, the insulated jacket 20 includes anysuitable protective and/or aesthetically pleasing outer materials.Examples of suitable materials for the insulated jacket 20, includefoams, polymers, metals, and the like. In a particular example, theinsulated jacket 20 includes expanded polypropylene (EPP). The EPPinsulated jacket 20 is configured to provide a structural jacket thatmay absorb kinetic impacts resiliently while also providing thermalinsulation. In some embodiments, the insulated jacket 20 may be madeexclusively of EPP and it is an advantage of these embodiments that theEPP material may be colored and have an aesthetically pleasing surfaceas well as providing sufficient structural and insulating properties.

As shown in FIG. 1, the insulated jacket 20 includes a plurality ofportions. These portions include structural, insulating, and aestheticfeatures that greatly improve the hot water heater appliance 10. Forexample, the insulated jacket 20 may include a bridge 22, top 24A,bottom 24B, front 24C, and back 24D. The bridge 22 or piping accesscover may be configured to provide insulation to the piping in the areabetween the boiler 12 and the companion water heater 14. In addition,the bridge 22 may be configured to aesthetically integrate the boiler 12and the companion water heater 14. It is an advantage of this aestheticintegration that the hot water heater appliance 10 may be located in ageneral living area of a domicile rather than closed away in a utilitycloset. It is another advantage of this aesthetic integration that theworking components of the companion water heater 14 are protected. It isyet another advantage of this aesthetic integration and the good surfaceproperties of EPP that the companion water heater 14 may collect lessdust than conventional water heaters and boilers and may be easier toclean. Also shown in FIG. 1, the insulated jacket 20 includes aplurality of openings disposed in cooperative alignment with respectiveinlets and outlets associated with the hot water storage tank 32.

The top 24A, bottom 24B, front 24C, and back 24D are configured toprovide the hot water storage tank 32 with insulation to each respectivearea. For example the top 24A is configured to insulate the top of thehot water storage tank 32 and reduce loss of heat therefrom via radiantloss, thermal conduction, air convection/infiltration and the like.Similarly, the bottom 24B, front 24C, and back 24D are configured toinsulate the bottom, front and back (including the sides) of the hotwater storage tank 32 and reduce loss of heat therefrom via radiantloss, thermal conduction, air convection/infiltration and the like.

In some embodiments, the portions of the insulated jacket 20 may beremovably attached to each other and/or the hot water storage tank 32.For example, the portions of the insulated jacket 20 may include anysuitable fastener such snaps, magnets, or the like that are configuredto attach to each other and/or to the hot water storage tank 32. Inparticular examples, the insulated jacket 20 includes a plurality offasteners 26A configured to align and attach the bridge 22 to the boiler12. In this manner, the aesthetic integration of the boiler 12 andcompanion water heater 14 may be further enhanced by the alignment ofone to the other. In addition, the insulated jacket 20 may includemagnetic fasteners 26B configured to releasably fasten the front 24C tothe back 24D. In this manner, the hot water storage tank 32 may beeasily accessed for maintenance evaluation and repair (e.g., welding orother such operation). In contrast, conventional hot water tanks aretypically covered in spray foam that renders the tank unserviceable.Another negative aspect of conventional spray foam installations is thatmoisture may be maintained in contact with the tank. The novel EPP‘clamshell’ insulated jacket 20 facilitated drawing or wicking moisturefrom the surface of the hot water storage tank 32.

Optionally, the top 24A and bottom 24B may include lips or otherstructures configured to releasably lock into slots, grooves or othersuch structures in the front 24C and back 24D. If included, thesestructures lock the top 24A and bottom 24B within the front 24C and back24D when the front 24C and back 24D are fastened and can be removed whenunfastened. In a particular example, the front 24C and back 24D includean annular top slot disposed about an inside portion of the front 24Cand back 24D configured to retain the top 24A. In another particularexample, the front 24C and back 24D include an annular bottom slotdisposed about an inside portion of the front 24C and back 24Dconfigured to retain the bottom 24B. Also optionally, the companionwater heater 14 may include leveling feet 28 configured to level andraise or lower the companion water heater 14 in a manner known to thoseskilled in the art.

The hot water storage tank 32 is configured to receive a supply ofdomestic cold water and utilize energy in the form of circulating boilerwater from the boiler 12 to provide a supply of domestic hot water. Thehot water storage tank 32 itself includes a shell of metal or other suchmaterial that is sufficiently strong to contain hot water at standardhousehold pressures of 50-70 pounds per square inch (psi) (345-483kilopascals ‘kPa’). The hot water storage tank 32 includes a heatexchange coil 50, exchange inlet 52, exchange outlet 54, DCW inlet 56,and DHW outlet 58.

The sensors 34 and 36 are configured to sense a temperature of the waterin the hot water storage tank 32 and forward a signal corresponding tothis sensed temperature to the controller 18. The sensors 34 and 36 mayinclude any suitable temperature sensing element such as, for example, athermocouple, thermistor, or the like. The sensor 34 may be placed inthermal contact with a lower portion of the hot water storage tank 32.In general, the lower portion of the water storage tank 32 representsthe lowest temperature in the water storage tank 32 due to therelatively higher density of colder water as compared to warmer waterand because the DCW inlet 56 is disposed at the lower portion of thewater storage tank 32. The sensor 36 may be placed in thermal contactwith an upper portion of the hot water storage tank 32. The upperportion of the water storage tank 32 generally represents to hottesttemperatures in the water storage tank 32. As such, the temperature atthe upper portion of the water storage tank 32 represents the hottestwater that can be delivered at that particular moment.

The mixing valve assembly 38 includes a thermostatic mixing valveconfigured to mix outgoing DHW with a controlled amount of incoming DCWto produce DHW at a predetermined maximum DHW temperature. Thispredetermined maximum DHW temperature may be set by the user or atechnician on the mixing valve assembly 38 and/or may be controlled bythe controller 18. This allows the hot water storage tank to store arelatively greater amount of thermal energy. In this manner, arelatively higher volume of DHW at the predetermined maximum DHWtemperature may be provided for a given volume of the hot water storagetank 32.

The circulator pump 40 is configured to urge water to flow or circulatebetween the boiler 12 and the heat exchange coil 50. The circulator pump40 is controlled via the controller 18. Typically, the circulator pump40 is controlled to start circulating the water or other heating fluidbetween the boiler 12 and the heat exchange coil 50 shortly before theboiler 12 begins to supply energy to the boiler water and then continuesto circulate for some predetermined time after the boiler 12 stopssupplying energy to the boiler water or until a predetermined cool downtemperature in the boiler is reached. The circulator pump 40 may,optionally, include a check valve to stop or reduce the flow of waterbetween the boiler 12 and the heat exchange coil 50 while the circulatorpump 40 is unpowered. This unpowered flow may draw out heat from the hotwater storage tank 32 if left unchecked.

The connectors 42 may include any suitable conduit and/or fittings forconveying boiler water between the boiler 12 and companion water heater14. In a particular example, the connectors 42 include flexiblestainless steel piping suitable for fluidly connecting the boiler 14 tothe companion water heater 14.

In general, the heat exchange coil 50 is configured to provide a conduitfor water or other heated fluid from the boiler 12 to be conveyedthrough the hot water storage tank 32 and to exchange the heat thereinwith the water in the hot water storage tank 32. Of note, the boilerwater and DHW are not mixed, but rather, heat from the boiler water isimparted upon the DHW through the material making up the heat exchangecoil 50. To efficiently exchange this heat, the heat exchange coil 50may be made from a conductive material such as metal and may have arelatively long, circuitous path. In addition, the heat exchange coil 50may optionally include radiating fins or other such implement toincrease thermal exchange. In other examples, the heat exchange coil 50may be an external, jacket-style heat exchange or other such heatexchanger.

FIG. 2 is a block diagram of a system architecture for the hot waterheater appliance 10 depicted in FIG. 1. As shown in FIG. 2, thecontroller 18 may be configured for two way communication between theboiler 12, user interface 16, sensors 34 and 36, and circulator pump 40.In addition, the controller 18 is optionally configured for two waycommunication between the mixing valve assembly 38 and/or an ambientsensor 64. In operation, the controller is configured to receive userinput from the user interface 16 and, based on this user input, controlthe various other components of the hot water heater appliance 10 toprovide DHW. The controller 18 may determine one or more aspects of thetemperature within the hot water storage tank 32 via the sensedconditions at the sensors 34 and 36. For example, if the temperature atthe sensor 34 is dropping relatively quickly, the controller 18 maydetermine DHW is being drawn out quickly (and DCW is being drawn inquickly to replace it). In another example, if the temperature at boththe sensors 34 and 36 are falling very slowly, then the controller 18may determine that little or no DHW is being drawn out. As such, thecontroller 18 may be able to accurately determine draw without the addedcomplication of a flow meter.

Control of the boiler 12 may include sensing temperatures at one or morelocations, sensing gas or fuel flow, ignition, ventilation control, andthe like. These and other aspects of controlling a conventionalnon-condensing or condensing boiler are generally known to those skilledin the art. If the optional ambient sensor 64 is included, thecontroller 18 is configured to sense the ambient temperature and theambient temperature may be factored into the control of the hot waterheater appliance 10. For example, temperature loss in the hot waterstorage tank 32 is a function of the difference in temperatures betweenthe hot water storage tank 32 and the ambient temperature. To reducethermal loss at time of relatively low ambient temperature, thecontroller 18 may maintain the temperature in the hot water storage tank32 at a relatively lower temperature. In another example, at times ofrelatively low ambient temperature, DHW water usage may rise or falldepending upon the habits of the users of the DHW. The controller 18 maybe configured to facture in ambient temperature in order to learn DHWusage trends. These DHW usage trends may be factored into the control ofthe hot water heater appliance 10 to supply sufficient DHW efficiently.

FIG. 3 is block diagram of the controller 18 for the hot water heaterappliance 10 depicted in FIG. 1. As shown in FIG. 3, the controller 18includes a processor 70. This processor 70 is operably connected to apower supply 72, memory 74, clock 76, analog to digital converter (A/D)78, and an input/output (I/O) port 80. The I/O port 80 is configured toreceive signals from any suitably attached electronic device and forwardthese signals to the A/D 78 and/or the processor 70. For example, theI/O port 80 may receive signals associated with temperature measurementsfrom one or more of the sensors 34, 36, and 64 and forward the signalsto the processor 70. In another example, the I/O port 80 may receivesignals via the user interface 16 shown in FIGS. 1 and 2 and forward thesignals to the processor 70. If the signals are in analog format, thesignals may proceed via the A/D 78. In this regard, the A/D 78 isconfigured to receive analog format signals and convert these signalsinto corresponding digital format signals. Conversely, the A/D 78 isconfigured to receive digital format signals from the processor 70,convert these signals to analog format, and forward the analog signalsto the I/O port 80. In this manner, electronic devices configured toreceive analog signals may intercommunicate with the processor 70.

The processor 70 is configured to receive and transmit signals to andfrom the A/D 78 and/or the I/O port 80. The processor 70 is furtherconfigured to receive time signals from the clock 76. In addition, theprocessor 70 is configured to store and retrieve electronic data to andfrom the memory 74. Furthermore, the processor 70 is configured todetermine signals operable to modulate the boiler 12 and thereby controlthe amount of heat imparted to the hot water storage tank 32. Forexample, in response to the processor 70 determining the water in thehot water storage tank 32 is below a predetermined minimum temperature,the processor 70 may forward signals to the various components of theboiler 12 and the circulator pump 40 to provide heat to the heatexchange coil 50 and thereby heat the water in the hot water storagetank 32.

According to an embodiment of the invention, the processor 70 isconfigured to execute a code 82. In this regard, the controller 18includes a set of computer readable instructions or code 82. Accordingto the code 82, the controller 18 is configured to modulate an amount ofenergy imparted into the hot water storage tank 32 by the boiler 12. Inaddition, the controller 18 may be configured to generate and store datato a file 84. This file 84 includes one or more of the following: sensedtemperatures; timestamp information; determined temperature profiles(e.g., rate at which the temperature is rising or falling); user inputtemperature profiles; recommended temperature profiles; DHW usagetrends; heating schedules of various performance modes; and the like.

Based on the set of instructions in the code 82 and signals from one ormore of the sensors 34, 36, and 64, the processor 70 is configured to:determine the thermal capacity presently in the hot water storage tank32; determine the temperature profile of the water in the hot waterstorage tank 32; determine the outflow of DHW from the hot water storagetank 32 based on the temperature profile; determine DHW usage trends;and determine whether the thermal capacity presently in the hot waterstorage tank 32 is sufficient for the expected usage based on DHW usagetrends or current water temperatures based on signals from the sensors34 and/or 36. For example, the processor 70 receives the sensedtemperature and/or an average sensed temperature, compares this toprevious temperatures over time to determine the current temperatureprofile. The processor 70 compares the current temperature profile toexpected thermal loss without DHW usage (e.g., standby loss) todetermine if usage is occurring and, if so, how much. In someperformance modes, the processor 70 determines whether this amount ofusage will exceed the thermal capacity of the hot water storage tank 32and may fire the boiler 12 proactively to prevent the temperature of theoutflow DHW from falling below a predetermined minimum. In otherperformance modes, the processor 70 may wait until the temperature ofthe outflow DHW falls below the predetermined minimum before controllingthe boiler 12 to fire. In addition, if the processor 70 determines thatno DHW draw is occurring, the processor 70 may wait until a draw occursbefore controlling the boiler 12 to fire. Optionally, processor 70 maybe configured to periodically raise the temperature above a biologicalkilling temperature in order to insure biological growth does not occur.For example, even if a user selects maximum temperature below thebiological killing temperature, the processor 70 may periodically raisethe temperature above the maximum temperature and the biological killingtemperature in order to ensure biological growth does not occur.

In various examples, knowing the temperature at the bottom and top ofthe hot water storage tank 32, by virtue of the sensors 34 and 36respectively, facilitates a greater flexibility and improved efficiencyas compared to systems without such capabilities. In a first example,the processor 70 may use information on incoming water temperature (assensed by the temperature sensor 34, for example) to adjust thetemperature profile to use the minimum energy needed to satisfy the DHWdemand. In a particular example, in the summer, warmer ground watertemperature would require less energy to raise the delivered DHW to thesame temperature as in the winter. As such, a lower boiler water delivertemperature may be able to satisfy the same flow rate in the summer as ahigher delivery temperature would in the winter. Lower boiler watertemperatures allow the boiler 12 to run at a higher efficiency.

In a second example, by knowing the temperature at both the top andbottom of the tank, the processor 70 may change the target boiler watertemperature during a DHW draw in order to most effectively meet thedemand. The processor 70 may increase the delivery temperature tofacilitate transferring maximum energy to the DHW. Also, in response tosignals from the sensor 36, the processor 70 may determine that the topof the hot water storage tank 32 has reached its targeted temperatureand may change (decrease) the target boiler water temperature in orderto limit the energy added to the top of the hot water storage tank 32while still adding energy to the colder water at the bottom of the hotwater storage tank 32. This feature of the processor 70 drasticallyincreases the thermal storage of the hot water storage tank 32 by addingthe maximum amount of energy to the hot water storage tank 32 whilepreventing the hottest water in the hot water storage tank 32 fromgreatly overshooting its target temperature and is a great improvementin the art. This symptom of overshooting a targeted DHW deliverytemperature is known to those familiar with the art as thermal stacking.Thermal stacking can, in some circumstances, lead to significantlyhotter DHW than desired due to adding excessive energy to the top of thestorage tank in order to recover the colder water in the tank to thedesired temperature. It is an advantage of embodiments described hereinthat significantly greater control over this negative performancecharacteristic is provided as compared to conventional storage waterheaters.

FIG. 4 is a block diagram of a method 100 of controlling the hot waterheater appliance 10 according to an embodiment of the present invention.Prior to performance of the method 100, the hot water heater appliance10 may be installed. It is an advantage of the hot water heaterappliance 10 that the various components to connect the boiler 12 to thehot water storage tank 32 are packaged as a kit and flexible to allowconnection to a variety of boiler configurations. For example, theboiler connectors 42 are flexible to allow for different placement ofinlet and outlet from the boiler 12. Prior to and/or during performanceof the method 100, various program parameters may be input and stored tothe file 84. For example, the user or a technician may select aperformance mode such as, for example: Off-Disabled which is generallyfor service; High performance which delivers the highest performance andmaximizes the thermal energy stored in the hot water storage tank 32;Normal performance which delivers a balance of performance and energyefficiency; Economy which delivers the most energy efficiency; Vacationmode which maintains the water in the hot water storage tank 32 at atemperature sufficient to deter freezing; and Scheduled which providesthe user with the capability to schedule different performance modes tobe performed at different times of the weekday and/or weekend; andLearning mode which may accept some initial user input and then learnDHW usage trends and alter the performance mode based on the DHW usagetrend.

At step 102, the controller 18 receives sensor measurements. Forexample, some or all of the sensors 34, 36, and 64 may forward signalscorresponding to the temperature sensed by the sensors to the controller18.

At step 104, the controller 18 may determine temperatures at the variouslocations, compare these sensed temperatures to target temperatures,determine one or more temperature profiles over time, and compare thoseone or more temperature profiles to predetermined temperatureprofile(s). For example, based on these forwarded signals, thecontroller 18 may determine the temperature at the lower and upperportion of the hot water storage tank 32 and, optionally, the ambienttemperature. These determined temperatures may be compared to a targettemperature range and/or a target temperature for the lower and upperportion of the hot water storage tank 32, respectively. If thedetermined temperatures fall outside the target temperature range orbelow the target temperatures, the controller 18 may be configured todetermine an action to rectify the determined temperatures. In aparticular example, if the determined temperatures at the upper portionof the hot water storage tank 32 falls below the target temperature forthe upper portion of the hot water storage tank 32, the controller 18may be configured to modulate the boiler at step 114 to increase theenergy delivered to the hot water storage tank 32.

As described herein, a large disparity in temperatures between the lowerand upper portion of the hot water storage tank 32 may lead to anunwanted condition of ‘thermal stacking’. It is an advantage ofembodiments described herein that the controller 18 may be configured toidentify temperature disparities that exceed a predetermined maximumtemperature variance and act to rectify the temperature disparity. In aparticular example, the controller 18 may be configured to lower theenergy in the boiler water delivered to the hot water storage tank 32via the heat exchange coil 50. As a result, energy can be imparted intoportions of hot water storage tank 32 with lower temperatures while notsignificantly raising the temperature of portions of hot water storagetank 32 with higher temperatures. In addition, depending on the boiler12 (e.g., heat source), generating lower energy boiler water may be moreefficient than generating higher energy boiler water. The efficienciesof the boiler 12 at various energy levels may be factored intodetermining the energy of the boiler water delivered to the hot waterstorage tank 32 via the heat exchange coil 50.

Over time, at step 104, a temperature profile may be determined for thelower and upper portion of the hot water storage tank 32 and,optionally, the ambient temperature.

At step 106, the controller 18 may be configured to determine DHW usage.For example, the temperature profiles of the lower and upper portion ofthe hot water storage tank 32 and/or an average thereof may be comparedto standby loss. If these profiles closely match or match within apredetermined amount, it may be determined that no DHW is being drawn.If these profiles do not match, the rate at which the sensed temperatureprofiles are falling may be used to determine DHW usage.

At step 108, the controller 18 may be configured to determine the amountof thermal energy presently stored in the hot water storage tank 32. Forexample, the temperature at the lower and upper portion of the hot waterstorage tank 32 may be used to determine an average temperature orcalculate a thermal gradient within the hot water storage tank 32 andthat value is then multiplied by the volume of water in the hot waterstorage tank 32.

At step 110, the selected performance mode may be factored into thedetermination about whether to add heat to the hot water storage tank32. For example in some performance mode, the controller 18 may beconfigured to add thermal energy to the hot water storage tank 32 inanticipation of outflow DHW falling below the predetermined minimum. Inother performance modes, the controller 18 may be configured to waituntil the temperature of the outflow DHW falls below the predeterminedminimum before adding thermal energy to the hot water storage tank 32.

In general, the various performance modes provide a combination ofoperating parameters of the hot water heater appliance 10 that providethe user of the hot water heater appliance 10 with the ability to selectone general mode over another without having to explicitly program eachoperating parameter. For example, if the user selects the ‘Economy Mode’and then a particular desired DHW temperature, the controller 18 may beconfigured to adjust the temperature at the upper portion of the hotwater storage tank 32 to be near or at the desired DHW temperature andalso control the boiler 12 to deliver boiler water to the hot waterstorage tank 32 at or slightly above the desired DHW temperature. Use ofthe performance modes greatly simplifies the operation of the hot waterheater appliance 10 for the user. Through calculations and lab testing,the performance modes have been developed that can be selected by theuser and that that optimize the parameters (tank storage temperature,boiler temperature, on/off temperature differentials, and others). Thesecan range from “Economy” mode to provide the best efficiency whenproducing hot water, “High Performance” mode that provides the maximumamount of hot water at the expense of efficiency, “Vacation” to use aminimum amount of energy to keep the hot water storage tank 32 fromfreezing, and other modes.

It is another benefit of some embodiments that the performance modes maybe scheduled by a technician or the user. The user interface 16 providesthe user with the ability to set the schedule of when the differentperformance modes may be active. For example, the “High Performance”mode may be scheduled in the morning hours when hot water usage is high.The hot water heater appliance 10 can be scheduled to then shift over toan “Economy” mode or even “Off” during times the building would not beoccupied. This differs from conventional DHW supply systems that requirethe contractor or user to program this schedule. In yet anotherembodiment, the scheduling of the various modes may be based onhistorical usage. For example, the hot water heater appliance 10 may beconfigured to learn that DHW usage increases at 7 am each weekdaymorning followed by a period of no usage for 9 hrs and then some smallDHW draws between 6 pm and 11 pm. These and other learned DHW usagehabits may then be used to develop a schedule that maximizes DHWavailability and efficiency.

At step 112, the controller 18 may determine whether or not to addthermal energy to the hot water storage tank 32. For example, thecontroller 18 may utilize the determined values, preset temperatures,preset performance mode. Based on the set of instructions in the code82, these and other factors may be weighed to determine if thermalenergy is to be added to the hot water storage tank 32. The plurality ofsensors 34 and 36 facilitates greater flexibility and efficiency of thesystem. The combination of the two sensors 34 and 36 can detect both thehigh temperature at the upper portion of the hot water storage tank 32as well as the lower temperatures at the lower portion of the hot waterstorage tank 32. Monitoring the current value of these sensors as wellas their rate of change can help the controller 18 determine theinferred load on the boiler 12. If the upper sensor 36 slowly drops intemperature, this can be indicative of a natural standby loss of thehottest part of the tank and the controller 18 can be configured to thenrespond with a high efficiency recovery because there is no immediateneed for hot water. If the lower temperature sensor 34 begins to dropthe controller 18 can determine if this is indicating a flow rate ofcold water coming into the hot water storage tank 32. This can be usedin lieu of a flow sensor with the added benefit of temperaturemeasurement that can be used for other functions. Based on the speed ofthe temperature decrease at the lower temperature sensor 34, thecontroller 18 can determine the size of the heat demand and the boiler12 or other such energy source can be controlled to respond accordingly.If the controller 18 detects a drop in temperature at the lower sensor34 followed by a drop in temperature at the upper sensor 36, this canindicate a very large flow/demand for hot water and the boiler 12 can becontrolled to aggressively add energy to the hot water storage tank 32to try to meet the demand and recover the tank temperature. Of note, thelocation and orientation of the sensors 34 and 36 depicted in FIG. 1 arefor illustrative purposes only and may each be located higher or loweron the hot water storage tank 32 and may be oriented in any suitablemanner.

In some DHW drawing circumstances, the controller 18 may determine thata total tank recovery procedure is warranted. In conventional systemswith a single sensor, overheating the tank is a common problem. Whentrying to recover the tank temperature with a high temperature in thecoil or inner tank (or any other type of heat exchanger) a portion ofthe domestic tank can experience overheating due to the fact that theboiler or energy source will continue to add heat to the tank until thesensor location has reached temperature. Often the sensor is not locatedat the highest temperature location in the tank, which causes the excessheat to be added to the tank. In various embodiments described herein,the controller 18 is configured to control the boiler 12 to deliver ahigh energy boiler water to recover the energy within the hot waterstorage tank 32 quickly, and then in response to the upper sensor 36 (orwherever the highest temperature sensor is located) sensing the targettemperature, the boiler 12 is controlled to deliver a lower energyboiler water to continue to add heat to the hot water storage tank 32without the potential or ability to heat any part of the hot waterstorage tank 32 over the desired value. In a particular example, theboiler 12 is controlled to deliver a boiler water at the targettemperature of the hot water storage tank 32 in response to thetemperature at the upper portion of the hot water storage tank 32 havingreached the target temperature but the lower portion of the hot waterstorage tank 32 still being below the target temperature. In thismanner, overheating is reduced or prevented while allowing the hot waterstorage tank 32 to reach a maximum amount of energy heat stored withinthe hot water storage tank 32. The boiler 12 may be controlled tocontinue to add energy until it can no longer modulate down any furtherbecause the hot water storage tank 32 is no longer absorbing energy andthe return water temperature coming back to the boiler increases and theoutlet water rises above the target temperature and the boiler 12 isthen controlled to shut off. This “Total Tank Recovery” has essentiallyfully charged the hot water storage tank 32 as if it was a thermalbattery. The first portion of the recovery being a high performance modeheating and the last portion of the recovery being performed at highefficiency mode heating.

If it is determined that thermal energy is to be added to the hot waterstorage tank 32, then, at step 114, the boiler 12 is controlled toincrease energy output and the circulator pump 40 is controlled to urgethe flow of water to circulate between the boiler 12 and the heatexchange coil 50. Following the step 114, it is determined if furtherthermal energy is to be added to the hot water storage tank 32 and thisis continued until it is determined that the hot water storage tank 32has sufficient thermal energy. Of note, in order to make thisdetermination, the temperature of the water in the hot water storagetank 32 is continually or periodically sensed. If it is determined thatthe hot water storage tank 32 has sufficient thermal energy, thetemperatures are sensed at step 102.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

What is claimed is:
 1. A hot water heater appliance, comprising: aboiler to heat a boiler water; a companion water heater to supply adomestic hot water; a heat exchange coil disposed in the companion waterheater configured to convey the boiler water through the heat exchangecoil and return the boiler water to the boiler; and a controllerconfigured to control the water heater appliance in response to ascheduled plurality of performance modes based on a preset schedule,wherein a first performance mode is configured to heat the domestic hotwater in the companion water heater solely by indirect heating from theboiler water supplied by the boiler, the domestic hot water in thecompanion water heater being heated to a predetermined temperaturerelatively more efficiently as compared to others of the plurality ofperformance modes by providing a supply of the boiler water to the heatexchange coil at a temperature that is the same as the predeterminedtemperature in the companion water heater and wherein less energy iswasted due to a difference in temperature between the boiler water andthe domestic hot water in the companion heater being reduced as comparedto others of the plurality of performance modes, the first performancemode is scheduled to be performed at an expected low usage time and asecond performance mode is configured to generate relatively greaterthermal energy stored in the companion water heater compared to othersof the plurality of performance modes by controlling a target boilerwater temperature, the second performance mode is scheduled to beperformed at an expected high usage time relative to the expected lowusage time.
 2. The hot water heater appliance according to claim 1,further comprising: a user interface to provide a display to the userand a keypad for the user to input settings.
 3. The hot water heaterappliance according to claim 1, further comprising: a hot water storagetank disposed in the companion water heater.
 4. The hot water heaterappliance according to claim 3, further comprising: a heat exchange coildisposed in the hot water storage tank.
 5. The hot water heaterappliance according to claim 4, further comprising: a lower sensordisposed in thermal contact with the lower portion of the hot waterstorage tank; and an upper sensor disposed in thermal contact with theupper portion of the hot water storage tank.
 6. The hot water heaterappliance according to claim 5, further comprising: a circulator pump tourge a flow of a heating fluid to circulate between a boiler and theheat exchange coil.
 7. The hot water heater appliance according to claim3, further comprising: an insulating jacket disposed around, below, andabove the hot water storage tank, the insulating jacket having anexpanded polypropylene insulation layer and the insulating jacketincluding a plurality of segments releasably fastened to each other. 8.The hot water heater appliance according to claim 1, further comprising:an ambient sensor to sense an ambient temperature.
 9. A companion waterheater comprising: a hot water storage tank; a heat exchange coildisposed in the hot water storage tank; a lower sensor disposed inthermal contact with a lower portion of the hot water storage tank; anupper sensor disposed in thermal contact with an upper portion of thehot water storage tank; a circulator pump to urge a flow of a heatingfluid to circulate between a boiler and the heat exchange coil; aninsulating jacket disposed around, below, and above the hot waterstorage tank, the insulating jacket having an expanded polypropyleneinsulation layer and the insulating jacket including a plurality ofsegments releasably fastened to each other; and a controller configuredto control the water heater appliance in response to a scheduledplurality of performance modes based on a preset schedule, wherein afirst performance mode is configured to heat water in the companionwater heater solely by indirect heating from the heating fluid suppliedby the boiler, the water in the companion water heater being heated to apredetermined temperature relatively more efficiently as compared toothers of the plurality of performance modes by providing a supply ofthe heating fluid to the heat exchange coil at a temperature that is thesame as the predetermined temperature in the companion water heater andwherein less energy is wasted due to a difference in temperature betweenthe heating fluid and the water in the companion heater being reduced ascompared to others of the plurality of performance modes, the firstperformance mode is scheduled to be performed at an expected low usagetime and a second performance mode is configured to generate relativelygreater thermal energy stored in the companion water heater compared toothers of the plurality of performance modes by controlling a targetboiler water temperature, the second performance mode is scheduled to beperformed at an expected high usage time relative to the expected lowusage time.
 10. The companion water heater according to claim 9, furthercomprising: a thermostatic mixing valve assembly.
 11. The companionwater heater according to claim 9, further comprising: an ambient sensorto sense an ambient temperature.
 12. The companion water heateraccording to claim 9, further comprising: a plurality of flexibleconnectors to fluidly connect the heat exchange coil with the boiler.13. The companion water heater according to claim 9, further comprising:a domestic hot water outlet fluidly connected to the hot water storagetank to supply domestic hot water.
 14. The companion water heateraccording to claim 13, further comprising: a domestic cold water inletfluidly connected to the hot water storage tank to replenish water drawnfrom the hot water storage tank.
 15. The companion water heateraccording to claim 12, further comprising: a temperature and pressurerelief valve fluidly connected to the hot water storage tank.
 16. Amethod of heating a domestic hot water in a water heater appliance, themethod comprising the steps of: receiving a plurality of upper portiontemperature measurements over a time period at a controller configuredto control the water heater appliance, the plurality of upper portiontemperature measurements being associated with an upper portion of a hotwater storage tank disposed in the water heater appliance; receiving aplurality of lower portion temperature measurements over the time periodat the controller from a lower portion of a hot water storage tank;determining an upper temperature profile over the time period by thecontroller based on the plurality of upper portion temperaturemeasurements; determining a lower temperature profile over the timeperiod by the controller based on the plurality of lower portiontemperature measurements; determining a domestic hot water usage amountby the controller in response to at least one of the upper temperatureprofile and the lower temperature profile being at a relatively steeperslope than a standby temperature profile; and heating the water inresponse to the domestic hot water usage being relatively greater thanan amount of thermal energy in the hot water storage tank; andscheduling a plurality of the performance mode to occur at predeterminedtimes; heating the domestic hot water in the companion water heatersolely by indirect heating from a boiler water supplied by a boiler, thedomestic hot water in the companion water heater being heated to apredetermined temperature relatively more efficiently as compared toothers of the plurality of performance modes by providing a supply ofthe boiler water to a heat exchange coil disposed in the companion waterheater at a temperature that is the same as the predeterminedtemperature in the companion water heater and wherein less energy iswasted due to a difference in temperature between the boiler water andthe domestic hot water in the companion heater being reduced as comparedto others of the plurality of performance modes in response to the firstperformance mode being scheduled; and controlling a target boiler watertemperature to generate relatively greater thermal energy stored in thehot water storage tank compared to others of the plurality ofperformance modes in response to a second performance mode beingscheduled.
 17. The method according to claim 16, further comprising thestep of: utilizing a performance mode stored to a computer file in thecontroller to determine when to heat the water in response to thedomestic hot water usage being relatively greater than an amount ofthermal energy in the hot water storage tank.
 18. The method accordingto claim 16, further comprising the step of: determining the thermalenergy in the hot water storage tank with the controller based on theplurality of upper portion temperature measurements and the plurality oflower portion temperature measurements.